On Wed, Aug 17, 2011 at 08:32:28AM -0700, Ping Cheng wrote: > On Tue, Aug 16, 2011 at 11:50 PM, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx > > wrote: > > > On Mon, Aug 15, 2011 at 09:34:23PM -0700, Ping Cheng wrote: > > > On Sun, Aug 14, 2011 at 8:27 PM, Chris Bagwell <chris@xxxxxxxxxxxxxx> > > wrote: > > > > > > > On Fri, Aug 12, 2011 at 7:08 PM, Ping Cheng <pinglinux@xxxxxxxxx> > > wrote: > > > > > Touch devices do not report valid pressure or capacitance. > > > > > > > > > > Signed-off-by: Ping Cheng <pingc@xxxxxxxxx> > > > > > --- > > > > > > > > I'd prefer if we kept pressure support. At least for Bamboo's with > > > > product ID between 0xd0 and 0xd4. > > > > > > > > In my testing of an 0xd1 device, pressure works fine (low pressure and > > > > high pressure work great. Not much middle pressure sensitivity. > > > > Multi-touch will increase pressure reading. All pretty common > > > > behaviour). > > > > > > > > > > Basically, there were three reasons to remove the pressure bit for all > > touch > > > devices: > > > > > > 1. The value is not a pressure and it does not report valid capacitance > > > either; > > > 2. The only valid use in the kernel driver is to decide if the finger > > is > > > touching the tablet or not, which has already been correctly reported by > > the > > > firmware in the other bits. So, it is redundant to check the pressure for > > > this purpose; > > > 3. Passing the invalid "pressure" to the user land would only introduce > > > bad user experience since touch is not designed for drawing. We don't > > want > > > to confuse user with that "pressure". > > > > Not speaking about touch per se, but pressure is important for other > > things besides drawing. Different people prefer different device > > sensitivity and if userspace knows pressure it can adjust according to > > user preference, like synaptics X driver does with touchpads that > > actually report it. I believe tslib allows similar for touchscreens. > > > > Your suggestion is based on the assumption that the value is pressure. I did not make any assumptions, I was just making general observation that if pressure data is available it is useful not only for drawing applications. > But > that is not true. The value is not pressure and it is unreliable. So what is this data then? Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
